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Apple Color RGB Monitor Troubleshooting Guide

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AppleColor RGB Monitor A2M6014
AppleColor RGB Monitor (Akbkuku, Wikimedia Commons, CC BY 4.0)

Fault-finding on the AppleColor RGB Monitor (A2M6014) for the Apple IIGS. Apple's method is to run its Adjustments Check first, make any adjustment that shows up, and only then go to the troubleshooting table and try the actions in the order listed.[1] The table works at board level: main logic (power supply) board, CRT video board, CRT, LED, switch and cord. For component-level work, the schematic is hosted with the Apple Color RGB Monitor Documentation.

Read CRT Discharge Procedure before opening the monitor, and Apple Color RGB Monitor General Maintenance for the take-apart and adjustments.

Adjustments Check

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Apple's check uses an Apple IIGS and the IIGS Diagnostic 1.0 diskette. Warm the monitor up for 15 minutes, set brightness to its centre click and contrast fully clockwise, then select patterns from Choose Tests, Video Pattern Tests.[2]

What each test pattern checks
Pattern Look for Adjustment
Super HiRes grid Top and bottom rows unequal, boxes stretched vertically, rolling, image high or low Vertical
Super HiRes grid Sides unequal, boxes stretched horizontally, tearing, image to one side, diagonal roll Horizontal
Super HiRes grid Boxes not all the same size Linearity
80 Col. Text Characters not sharp Focus
Color Bars Colour wrong Colour

Troubleshooting table

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Actions in Apple's order.[1]

AppleColor RGB Monitor troubleshooting table (Technical Procedures pp. 4.7-4.9)
Symptom Actions
Power switch on, LED off, no raster Check the mains outlet; replace the main logic/power supply board; the CRT video board; the AC cord assembly; the on/off switch
Power switch on, LED on, no raster Check the video cable; adjust the external brightness and the contrast; check fuse F901 on the main logic board and replace it if blown; check all connectors on both boards; replace the main logic board; replace the CRT video board
Raster but LED off Replace the LED assembly; replace the CRT video board
One horizontal line Check that the internal SERVICE switch S691 is down (normal); check the yoke wires and connector; replace the main logic board; replace the CRT
One vertical line Check the yoke wires and connector; replace the main logic board; replace the CRT
One side of the raster taller than the other Replace the CRT
Abnormal raster Check all connectors; replace the main logic board
Horizontal or vertical linearity will not adjust Replace the main logic board
High-pitched noise Replace the main logic board
Small, abnormally bright raster Check the yoke connector; replace the main logic board; the CRT video board; the CRT
No vertical sync Adjust the rear vertical hold; replace the main logic board
Raster will not centre Replace the main logic board
Colour, contrast or brightness will not adjust Replace the main logic board; replace the CRT video board
Characters jitter Check all ground straps; check that nearby computer equipment is properly grounded; replace the main logic board; the CRT video board
Black spot remains after switch-off (burnt phosphor) Replace the CRT
Picture too dark or too bright Adjust the external brightness; replace the main logic board; the CRT video board
Out of focus Replace the main logic board; replace the CRT
Raster one predominant colour Do the colour adjustment; replace the CRT video board; the main logic board
No colour Check that the software displays in colour; replace the CRT video board; the main logic board
Monitor shuts down H-HOLD (VR502) misadjusted: switch off, centre the control, switch on and repeat the adjustment; replace the main logic board
Flashing or wavy screen Gently crimp the metal connector tabs on the video connector

If the fault is still there after the table, Apple sent its technicians to the Regional Technical Support Center.[1]

Things that are not faults

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  • The monitor switching itself off during horizontal adjustment is its protection circuit reacting to VR502 being turned too far. Centre the control and wait 30 seconds.[3]
  • A single horizontal line after someone has been inside can be the SERVICE switch left up after a colour set-up.[1]

Self-inflicted faults

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  • The main logic board must run between the notches in its metal tray, or it can short against the tray.[4]
  • Liquid on the CRT funnel damages its conductive coating.[5]
  • Sliding fuse F901 sideways can break its holder.[6]
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References

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  1. ↑ 1.0 1.1 1.2 1.3 Apple Computer, AppleColor RGB Monitor Technical Procedures, in Apple Service Technical Procedures: Apple II Family, Volume Two, 072-0229, November 1991 build, Troubleshooting, pp. 4.2-4.9 (PDF pp. 52-59). Hosted here: File:AppleColor RGB Monitor Technical Procedures.pdf.
  2. ↑ AppleColor RGB Monitor Technical Procedures, Troubleshooting, Adjustments Check Procedure, pp. 4.3-4.6 (PDF pp. 53-56).
  3. ↑ AppleColor RGB Monitor Technical Procedures, Adjustments, Horizontal Adjustments, p. 3.7 (PDF p. 41).
  4. ↑ AppleColor RGB Monitor Technical Procedures, Take-Apart, Main Logic (Power Supply) Board, p. 2.16 (PDF p. 24).
  5. ↑ AppleColor RGB Monitor Technical Procedures, Take-Apart, Cathode-Ray Tube, p. 2.20 (PDF p. 28).
  6. ↑ AppleColor RGB Monitor Technical Procedures, Take-Apart, Main Logic Board Fuse, p. 2.26 (PDF p. 34).


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